This invention relates to features of an electric motor drive assembly that can be used in an existing vehicle or a new vehicle, such as a car.
Present day internal combustion engine four wheel cars are not as efficient as most electric cars because of the losses in the internal combustion engines and the mechanical drive train.
Modern all electric four wheel vehicles commonly use one or more motors and some form of mechanical transmission or mechanical differential arrangement to deliver power to the drive wheels. Such arrangements are basically conventional and are less efficient because of the losses in the mechanical transmission and mechanical differential that drive the wheels. The losses are compounded if the electric drive train is also coupled to an internal combustion engine, such as in a hybrid configuration. Generally the losses in this type of electrical drive train can be expected to be less than the total losses in an all internal combustion engine drive car with a conventional mechanical transmission and mechanical drive train.
Drive assemblies including one or more electric motors for delivering power to the drive wheels of a vehicle have been developed, with more lately-developed drive assemblies having done away with the conventional mechanical transmission or mechanical differential arrangement, or both as shown in U.S. Patent Application Publication Nos. 2011/0114399; 2011/0115321; 2011/0115320 and International Publication No. WO 2011/060362, each of which is expressly incorporated in its entirety herein. In one example, a drive assembly includes two electric motors, with the output shaft of each motor being connected to a planetary gear assembly. The planetary gear assembly is, in turn, connected to a wheel through an axle and one or more continuous velocity joints. A conventional mechanical transmission is unnecessary in such an assembly because the electric motors deliver high torque and speed and are capable of delivering appropriate amounts of torque and speed for typical driving needs. And, because the output of the electric motors drives the planetary gear assembly, which, in turn is connected to a wheel by an axle and one or more continuous velocity joints, a conventional mechanical differential is also unnecessary.
In a working environment, such as in a vehicle, the components of these types of drive assemblies can be closely situated and can generate heat when used. Maintaining suitable operating conditions, such as temperature, is an important concern for the operation and longevity of the drive assemblies. Cooling systems have been used with internal combustion engines to remove excess heat and control operating temperatures. But, because some electric motor drive assemblies for vehicles are of relatively recent design and new developments are underway, their cooling systems have not reached a mature stage.
Thus, a need exists in the art for features of an electric motor drive assembly for controlling the temperature in the drive assembly, thereby facilitating the efficiency advantages of electric vehicles.